1. Field of the Invention
The present invention relates to a system for managing copyrights for using, storing, copying, editing, or transferring digital data, particularly in multimedia applications.
2. Background Art
In the information-oriented society of today, database systems are becoming wide spread in which it is possible to use various types of data, stored independently in each computer in the past, by connecting computers via communication lines.
In such a database system, the information handled up to this point has been conventionally coded information that can be processed by a computer, and that contains a relatively small amount of information and monochrome binary data, such as facsimile information at most. It is not possible to handle data containing a relatively large amount of information, such as data for natural pictures or animation.
With the rapid progress of digital processing technique for various electric signals, a technique is under development for digital processing of picture signals other than binary data, handled only as analog signals in the past
By digitizing the picture signal, it is possible to handle a picture signal, e.g., a television signal, by a computer. xe2x80x9cMultimedia systemsxe2x80x9d is an emerging technology of the future capable of simultaneously handling the data handled by computers and digitized picture data.
Because picture data contains an overwhelmingly large amount of information compared with character data and audio data, it is difficult to store or transfer or process the picture data by computer. For this reason, techniques for compressing or expanding picture data have been developed. Further, several standards for compression/expansion of picture data have been established. For example, the following standards have been established as common standards: JPEG (Joint Photographic image coding Experts Group) standards for still pictures, H.261 standards for video conferences, MPEG1 (Moving Picture image coding Experts Group 1) standards for picture accumulation, and MPEG2 standards for current television broadcasting and high definition television broadcasting. By using these new techniques, it is now possible to transmit digital picture data in real time.
For analog data, which has been widely used in the past, the control of copyrights during processing has not been an important issue because the quality of the analog data deteriorates each time the data is stored, copied, edited, or transferred, the editing of a copyright produced due to the above operation has not been a large problem. However, the quality of digital data does not deteriorate when the data is repeatedly stored, copied, edited, or transferred. Therefore, the management and control of copyrights during processing of digital data is an important issue.
Up to now, there has been no adequate method for management and control of copyrights for digital data. It has been managed and controlled merely by copyright law or by contracts. In copyright law, only compensation for digital sound or picture recording devices has been prescribed.
It is possible not only to refer to the content of a database, but also to effectively utilize the data obtained from the database by storing, copying, or editing the data, and also transferring the edited data to the database with the edited data registered as new data. Further, it is possible to transfer edited data to other persons via a communication link or by a proper recording medium.
In a conventional database system, only character data is handled. However, in multimedia systems, sound data and picture data originally generated as analog data, are digitized and used as part of the database in addition to the other data in the database such as character data.
Under such circumstances, it is an important question to determine how to handle copyrights of the data in the database. However, there are no means in the prior art for copyright management and control of such actions as copying, editing, transferring, etc. of data.
The inventors of the present invention proposed a system for copyright management, wherein a permit key is obtained from a key control center via a public telephone line in Japanese Patent Laid-Open No. 46419/1994 and Japanese Patent Laid-Open No. 141004/1994. Japanese Patent Laid-Open No. 132916/1994 to the same inventors also discusses an apparatus for copyright management and control.
The database copyright management system of the prior applications use one or any combination of the copyright control program, the copyright information, and the copyright control message in addition to a permit key corresponding to a request.
The copyright control message is displayed on a screen and advises or warns the user if the data is utilized in a manner inconsistent with the user""s request permission. The copyright control program watches and controls data use so that the data is not utilized beyond the conditions of the user""s request or permission.
The copyright control program, the copyright information and the copyright control message are supplied together with a permit key in some cases, but they may be supplied with data in other cases. It is also possible to supply a part of them together with the permit key, and to supply the other part with the data.
For the data, the permit key, the copyright control message, the copyright information, or the copyright control program, there are the following three cases: they are transmitted in encrypted form and decrypted upon use; they are transmitted in encrypted form and decrypted only when they are displayed; or they not encrypted at all.
The present invention provides a data copyright management system comprising a database for storing original data, a key control center for managing a crypt key, a copyright management center for managing a data copyright. A communication network is provided to connect the database, the key control center, and the copyright management center, wherein data from the database is encrypted and the user decrypts the data with a crypt key obtained from the key control center or the copyright management center.
For supplying data to a user, there are the following two methods: a one-way communication of encrypted data to the user such as by broadcasting; and a two-way communication of encrypted data to the user in accordance with the user""s request.
Different schemes are available for a cryptographic system: a secret-key cryptosystem, a public-key cryptosystem, or a system combining a secret-key and a public-key. A cryptographic system further uses a copyright control program for managing data copyrights.
When a user stores, copies, or transmits data, the data is encrypted by a crypt key, which is obtained from the key control center or from the copyright management center, or generated by the copyright control program.
The present invention can be applied to copyright control not only a single data value but also a plurality of data values from a single database or a plurality of data values supplied from a plurality of databases. Further, an apparatus is also proposed for performing data copyright management.